Apparatuses and methods for controlling data timing in a multi-memory system

ABSTRACT

Apparatuses, multi-memory systems, and methods for controlling data timing in a multi-memory system are disclosed. An example apparatus includes a plurality of memory units. In the example apparatus, a memory unit of the plurality of memory units includes a memory configured to provide associated read data to a data pipeline based on row control signals and column control signals. The memory unit further includes local control logic configured to provide the row control signals and the column control signals to the memory; and a configurable delay circuit coupled between the local control logic and the memory, the configured to delay receipt of the column control signals to the memory.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.15/626,915, filed Jun. 19, 2017, which is a continuation of U.S. patentapplication Ser. No. 13/804,461, filed Mar. 14, 2013, and issued as U.S.Pat. No. 9,715,909 on Jul. 25, 2017. The aforementioned applications andpatent are incorporated herein by reference, in their entirety, and forany purposes.

TECHNICAL FIELD

Embodiments of the disclosure relate generally to electronic memories,and more particularly, in one or more of the illustrated embodiments, tocontrolling the timing of when data is provided to a data pipeline bymemory units in a multi-memory system.

DESCRIPTION OF RELATED ART

Advances in technology have resulted in high density memoryarchitectures. The high density memory architecture has led tomulti-memory systems that include several memory units. An examplemulti-memory system is a stacked memory stem including several memoryunits stacked together. In order to make the multi-memory systemtransparent to external controllers, communication with individualmemory units of a multi-memory system is facilitated through a memoryunit identified as a master memory unit. The master memory unit receivesthe commands, addresses, and data and controls the operation of theother memory units of the multi-memory system. In some examples, alldata read from and written to the multi-memory system is funneledthrough a shared data pipeline on the master memory unit. In existingmulti-memory systems, delta timing between consecutive memory accesscommands is used to control data flow to the data pipeline. As minimumtiming requirements between consecutive access commands continue tobecome more compressed, slight timing characteristic differences betweenindividual memory units in the multi-memory system may result in datacollisions at the data pipeline. Thus, accounting for relative timingdifferences between the individual Memory units in providing data to thedata pipeline is desired to improve operability of the multi-memorysystem.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a particular illustrative embodiment of amulti-memory;

FIG. 2 is a block diagram of a particular illustrative embodiment of aconfigurable delay circuit;

FIG. 3 is an exemplary timing diagram of a particular illustrativeembodiment of a multi-memory system;

FIG. 4 is an exemplary timing diagram of a particular illustrativeembodiment of a multi-memory system with configurable delay circuits;

FIG. 5 is a block diagram of a particular illustrative embodiment ofrelative timing measurement circuit of a multi-memory system; and

FIG. 6 is an illustration of a multi-memory system according to oneembodiment of the disclosure.

DETAILED DESCRIPTION

Certain details are set forth below to provide a sufficientunderstanding of embodiments of the disclosure. However, it will beclear to one having ordinary skill in the art that embodiments of thedisclosure may be practiced without these particular details. Moreover,the particular embodiments of the present disclosure described hereinare provided by way of example and should not be used to limit the scopeof the disclosure to these particular embodiments.

Referring to FIG. 1, a particular illustrative embodiment of anapparatus including a multi-memory system is disclosed and generallydesignated apparatus 100. As used herein, examples of apparatuses mayinclude, an integrated circuity a memory device, a memory system, aaelectronic device or system, a smart phone, a tablet, a computer, aserver, etc. The multi-memory system in some embodiments is a stackedmulti-memory system including multiple memory units stacked on oneanother. The apparatus 100 may include a master memory unit 102 and aslave memory unit 104 that share a common data pipeline 160 located onthe master memory unit 102 to provide I/O data to and from themulti-memory system. The master memory unit 102 and the slave memoryunit 104 may exhibit slightly different timing characteristics, forexample, due to process inconsistencies during fabrication, differingoperating conditions, etc. Thus, due to the differences in timingcharacteristics and because the master memory unit 102 and the slavememory unit 104 share the common data pipeline 160, data collisions mayoccur at the data pipeline 160 when the master memory unit 102 and theslave memory unit 104 provide data to the data pipeline 160 at the sametime. Delaying operation of the master memory unit 102 and or the slavememory unit 104, and thereby delaying provision of data to the datapipeline 160, via a configurable delay circuit (DLY) 130(0) and/or aconfigurable delay circuit 130(1), respectively, may improve reliabilityof the apparatus 100. It is appreciated that, while FIG. 1 depicts asingle slave memory unit 104, the apparatus 100 may include any numberof additional slave memory units in addition to the slave memory unit104. For example, memory units according to embodiments of the presentdisclosure may be included in multi-memory systems having 4, 16, 32, andso on, memory units. In some embodiments the master memory unit 102 andthe slave memory unit 104 may be identical. Accordingly, each of themaster memory unit 102 and the slave memory unit 104 may have the samearchitecture, including memory addressing, with some circuitry orcomponents designated for the master memory unit 102 disabled on theslave memory unit 104.

The master memory unit 102 may include control logic 110 configured toreceive control signals CTRL from an external source (not shown), suchas a memory controller. Responsive to the CTRL signals, the controllogic 110 may pro-vide associated control signals CSM to local controllogic 120(0) of the master memory unit 102 and slave control signals CSSto local control logic 120(1) of the slave memory unit 104. The localcontrol logic 120(0) may be configured to provide, to the memory 140(0),master row control signals RCSM to the memory 140(0) via row controllogic 124(0) and column control signals CCSM via column control logic122(0) and through the configurable delay circuit 130(0). In someembodiments, the configurable delay circuit 130(0) may be configured todelay receipt of the CCSM signal at the memory 140(0) based on a valueindicated by a fuse bank 134(0). For example, the configurable delaycircuit 130(0) may include a plurality of delay gates, and a number ofactive delay gates of the plurality of delay gates of the configurabledelay circuit 130(0) may be based on a value indicated via the fuse bank134(0). The configurable delay circuit 130(0) delays receipt of the CCSMsignal at the memory 140(0) by providing the CCSM signal through theactive delay gates of the configurable delay circuit 130(0). Responsiveto receiving the CCSM signal the memory 140(0) may initiate a columnstart operation as part of a memory access operation. The column startoperation may result in the memory 140(0) providing data to the datapipeline 160 based on the RCSM and CCSM signals. The memory 140(0) mayalso be configured to provide a control signal QINM to a control buffer(CTRL) 150 via a connection point 192 contemporaneously with provisionof the data to the data pipeline 160. The control buffer 150 may provideassociated control signals QIN<i> based on the QINM signal to direct thedata pipeline 160 to store the data provided by the memory 140(0).

Referring to the slave memory unit 104, the local control logic 120(1)may be configured to provide, to the memory 140(1), row control signalsRCSS via row control logic 124(1) to the memory 140(1) and columncontrol signals CCSS via column control logic 122(1) and through theconfigurable delay circuit 130(1). In some embodiments, the configurabledelay circuit 130(1) may be configured to delay receipt of the CCSSsignal at the memory 140(1) based on a value indicated by a fuse bank134(1). Similar to the configurable delay circuit 130(0), theconfigurable delay circuit 130(1) may include a plurality of delaygates, and a number of active delay gates of the configurable delaycircuit 130(1) may be based on a value indicated via the fuse bank134(1). The configurable delay circuit 130(1) mas be configured to delayreceipt of the CCSS signal at the memory 140(1) by providing the CCSSsignal through the active delay gates of the configurable delay circuit130(1). Responsive to receiving the CCSS signal, the memory 140(11 mayinitiate a column start operation as part of a memory access operation.The column start operation may result in the memory 140(1) providingdata to the data pipeline 160 via a connection point 190 based un theRCSS and CCSS signals. The memory 140(1) may also be configured toprovide a control signal QINS to the control buffer 150 via theconnection point 192 contemporaneously with provision of the dam fromthe memory 140(1) to the data pipeline 160. The control buffer 150 mayfurther provide the associated control signals QIN<i> based on the QINSsignal to direct the data pipeline 160 to store the data. In someembodiments, the CTRL buffer 150 may include a first in, first out FIFObuffer to provide the associated control signals QIN<i >.

In operation, the control logic 110 may receive CTRL signals, such as amemory command (e.g., memory read request, a memory write request), aclock, a clock enable, a write enable, a chip select signal, etc., andaddress signals to perform a memory access operation. Based on values ofthe CTRL signals, the control logic 110 may be configured to providecontrol signals (e.g., the CSM signal or the CSS signal), to the localcontrol logic 120(0) or the local control logic 120(1), respectively.For the master memory unit 102, responsible to receiving the CSM signal,the local control logic 120(0) may be configured to provide row controlinformation to the memory 140(0) via the RCSM signals. Followingprovision of the row control information via the RCSM signal, the localcontrol logic 120(0) may be configured to provide column controlinformation to the memory 140(0) via the CCSM signal. At the memory140(0), responsive to receipt of the row control information receivedvia the RCSM signals, the memory 140(0) may be configured to initiate amemory access operation based on the row control information Responsiveto receipt of the column control information via the CCSM signal, thememory 140(0) may be configured to continue the memory access operationby initiating a column start operation based on the column controlinformation. The column start operation may result in the memory 140(0)being configured to retrieve data based on the row control informationand the column control information, and to provide the data to the datapipeline 160 and the QINM signal to the CTRL buffer 150 via theconnection point 192, contemporaneously.

The slave memory unit 104 may be configured to operate similarly to themaster memory unit 102. Thus, responsive to receiving the CSS signal,the local control logic 120(1) may be configured to provide row controlinformation to the memory 140(1) via the ROSS signal. Followingprovision of the row control information via the RCSS signal the localcontrol logic 120(1) may be configured to provide column controlinformation to the memory 140(1) via the CCSS signal. At the memory140(1), responsive to receipt of the row control information receivedvia the RCSS signal, the memory 140(1) may be configured to initiate amemory access operation based on the row control information. Responsiveto receipt of the column control information via the CCSS signal, thememory 140(1) may be configured to continue the memory access operationby initiating a column start operation based on the column controlinformation. The column start operation may result in the memory 140(1)being configured to retrieve data based on the row control informationand the column control information, and to provide the data to the datapipeline 160 and the QINS signal to the CTRL buffer 150,contemporaneously. The memory 140(1) may be coupled to the master memoryunit 102 via the connection points 100 and 192, such as athrough-silicon vias, in order to provide data and the QINS signal fromthe memory 140(1) to the data pipeline 160. The QINM signal and QINSsignal may exhibit the same delay characteristics to the data pipeline160 relative to one another, and relative to delay characteristics of adata path along which the data is provided from the memory 140(0) andthe memory 140(1), respectively, to the data pipeline 160. Thus, theQINM signal and the QINS signal may each be routed through theconnection point 192 in order to match a delay of the data along thedata path through the connection point 100 that is used to provide datafrom the memory 140(1). In some embodiments, the QINM signal may berouted through a load circuit on the master memory unit 102 thatemulates a load of the connection point 192.

The control buffer 150 may provide the associated QIN<i> signalsdirecting the data pipeline 160 to store the data from the memory 140(0)and the data from the memory 140(1) contemporaneous with receipt of therespective data at the data pipeline 160. In some embodiments, thecontrol buffer 150 may be omitted, and the QINM signal may be providedto the data pipeline by the master memory unit 102 to direct the datapipeline to store data from any of the memory units, including the slavememory unit 104.

As explained above, the master memory unit 102 and the slave memory unit104 may have the same architecture and/or may be fabricated using thesame process. However, certain characteristics may vary between themaster memory unit 102 and the slave memory unit 104 due to variabilityin the fabrication process. As a result, the master memory unit 102 andthe slave memory unit 104 may exhibit differences in timingcharacteristics. Thus, the timing of when data is provided by arespective memory 140 to the data pipeline 160 responsive to a memorycommand (e.g., a read command) may be different for the master memoryunit 102 and the slave memory unit 104, which may result in datacollisions at the data pipeline 160 for consecutive memory commands. Forexample., if a timing characteristic of the master memory unit 102 has adelay from the master local control logic 120(0) to the data pipeline160 that is greater relative to a delay from the slave local controllogic 120(1) to the data pipeline 160, data provided from the mastermemory unit 102 may collide with data provided from the slave memoryunit 104 for consecutive memory commands.

Accordingly, a control signal that causes a memory to output data may bedelayed, and as a result, may alter the timing of when data is outputrelative to a memory command. For example, the configurable delaycircuit 130(0) and/or the configurable delay circuit 130(1) may beconfigured to delay receipt of respective column control information viathe CCSM and/or CCSS signals at the memory 140(0) and/or the memory140(1), respectively. A length of a delay through the configurable delaycircuit 130(0) and/or the configurable delay circuit 130(1) may bedetermined based on relative timing characteristic differences betweenthe master memory unit 102 and the slave memory unit 104. These relativetiming characteristic differences may be measured as described, furtherwith reference to FIG. 5. In some embodiments, a configurable delaycircuit of a memory unit having a longest latency (e.g., a slowestmemory unit) may be configured to have a minimal delay (e.g., zero delaygates activated) based on a corresponding fuse bank. Further,configurable delay circuits of other memory units may have delaysgreater than the minimal delay (e.g., one or more active delay gates)based on a respective fuse bank, such that the respective delay (e.g.,number of active delay gates) approximates a respective relative timingcharacteristic difference as compared with the slowest memory unit.

For example, with reference to the apparatus 100, which includes twomemory units, the master memory unit 102 may be determined to have atiming characteristic that is 12 gates (e.g., 12 g) slower than theslave memory unit 104. Thus, the master memory unit 102 is determined tobe the slowest of the two memory units. Accordingly, the master fusebank 134(0) has a value indicating zero active delay gates of theconfigurable delay circuit 130(0) (e.g., the CCSM Signal is minimallydelayed through the configurable delay circuit 130(0)). Responsive tothe configurable delay circuit 130(0) having zero active delay gates,the CCSM signal is received at the memory 140(0) with minimal delay.Further, the slave fuse bank 134(1) may have a value indicating 12active delay gates of the configurable delay circuit 130(1). Responsiveto the configurable delay circuit 130(1) having 12 active delay gates,the CCSS signal is received at the memory 140(1) after delay though 12delay gates. Delaying receipt of the CCSS signal at the memory 140(1)may accordingly delay when data is provided from the memory 140(0) tothe data pipeline 160 (e.g., by delating receipt of the respectivecolumn control information, initiation of the column start operation ofthe memory access operation is delayed accordingly, as described above).Further, delay of the CCSS signal may also delay provision of the QINSsignals to the control buffer 150, such that the data from the memory140(1) and the associated QINS signal are provided from the memory140(1) contemporaneously. In this example, delaying the CCSS signal,(and as a result delaying when data is provided by the memory 140(1))may reduce likelihood of a data collision at the data pipeline 160between the data from the memory 140(0) and the data from the memory140(1) for consecutive memory commands.

It will be appreciated that selection of a delay through a respectiveconfigurable delay circuit may depend on a resolution of theconfigurable delay circuit. Thus, the delay set in the configurabledelay circuit, may be an approximation of the relative timing differencewith the memory unit having the slowest relative timing as allowed bythe configurable delay circuit. For example, if it is determined thatrelative timing between a memory unit and the slowest memory unit is 15g, and delays available at the configurable delay circuit of the memoryunit are 12 g and 16 g, the memory unit may select the log delay. Inother embodiments, the memory unit may select set the configurable delaycircuit to a delay that approximates the relative timing differencewithout being greater than the relative timing difference, and, thus,may set the delay circuit to the 12 g delay. In some embodiments, timingcharacteristics and relative differences between timing characteristicsmay be determined during production, and the fuse banks (e.g., the fusebank 134(0) and the fuse bank 134(1)) may be programmed at that time.The fuse bank 134(0) and/or the fuse bank 134(1) may includeprogrammable elements In some embodiments, the fuse bank 134(0) and/orthe fuse bank 134(1) may include fuses, anti-fuses, or a combinationthereof. In other embodiments, the timing characteristics may bedetermined periodically in the field. Thus, the number of active delaygates of a configurable delay circuit may be controlled based on anassociated delay control signal for each memory unit. Each respectivedelay control signal may be provided by the control logic 110, in someembodiments.

Referring to FIG. 2, a particular illustrative embodiment of aconfigurable delay circuit is disclosed and generally designated 230.The configurable delay circuit 230 may include a delay architectureconfigured to provide an output signal OUT at an output based on aninput signal IN through the configurable delay circuit 230. Theconfigurable delay circuit 230 may be used for the configurable delaycircuit 130(0) or the configurable delay circuit 130(1) of FIG. 1.

The configurable delay circuit 230 may include cascading delay stages(e.g., a 4 g delay stage 232, an 8 g delay stage 236, and an 8 g delaystage 238), each configured to provide an IN signal to a multiplexer 234after an associated delay. In some embodiments, the multiplexer 234 is afour input multiplexer configured to receive the IN signal at a firstinput (e.g., no delay), the IN signal delayed through the 4 g delaystage 232 at a second input, the IN signal delayed through the 4 g delaystage 232 and the 8 g delay stage 236 at a third input, and the INsignal delayed through the 4 g delay stage 232, the 8 g delay stage 236,and the 8 g delay stage 238 at a fourth input. In an example, the 4 gdelay stage 232 is a 4 gate (g) delay, the 8 g delay stage 236 is an 8 gdelay, and the 8 g delay stage 238 is an 8 g delay. Thus, the firstinput may be a 0 g delay, the second input may be a 4 g delay, the thirdinput may be a 12 g delay, and the fourth input may be a 20 g delay. Itis appreciated that the 4 g delay stage 232, the 8 g delay stage 230,and the 8 g delay stage 238 may have any combination of delay lengths.The 4 g delay stage 232, the 8 g delay stage 236, and the 8 g delaystage 238 may include a plurality of delay gates, such as may includeinverters, NAND gates, etc., to produce an associated delay length. Themultiplexer 234 is configured to provide the OUT signal based on one ofthe four inputs via a buffer 239. In some embodiments, the multiplexer234 is configured to select one of the four inputs to provide at theoutput responsive to a value of the DLY CTRL signal. The DLY CTRL signalmay be provided by or derived from via an associated fuse bank, such asthe fuse bank 134(0) or fuse bank 134(1) of FIG. 1.

While FIG. 2 depicts the multiplexer 234 as a four-input multiplexer,the multiplexer 234 may be replaced by four switching elements (e.g.,transistors, tri-state inverters, etc.), with a respective switchingelement coupled between an associated input of the multiplexer 234 andthe buffer 239. Further, the configurable delay circuit 230 may beconfigured with more or less than three delay stages, and each delaystage may have any number of delay gates.

Referring to FIGS. 3 and 4, exemplary timing diagrams of a particularillustrative embodiment of multi-memory system timing, where data accesstiming of a memory of a slave memory unit is faster relative to dataaccess timing of a memory of a master memory unit. For example, anexemplary timing diagram 300 may illustrate timing characteristics ofthe apparatus 100 of FIG. 1 without the configurable delay circuit130(0) or the configurable delay circuit 130(1), and an exemplary tuningdiagram 400 may illustrate timing characteristics of the apparatus 100of FIG. 1 including the configurable delay circuit 130(0) or theconfigurable delay circuit 130(1). Clock signal (CLK) 310 represents aclock signal used to time receipt of mentors commands by a multi-memorysystem: first master memory command RDM1 312 at time 10 first slavememory command RDS1 316 at time T1, second master memory command RDM2314 at time T2, and second slave memory command RDS2 318 at time T3. TheRDM1 312 and RDM2 314 memory commands are directed to a master memoryunit, such as the master memory unit 102 of FIG. 1. The RDS1 316 andRDS2 318 memory commands are directed to a slave memory unit, such asthe slave memory unit 104 of FIG. 1.

Column control signal CCS 320 represents exemplary relative timing ofreceipt of the CCS signal 320 at the respective memory based on therespective memory command. For example, the CCSM1 signal 322, associatedwith the RDM1 command 312 is received at the memory of the master memoryunit (e.g., memory 140(0)) at a first time, the CCSS1 signal 326,associated with the RDS1 command 316, is received at the memory of theslave memory unit (e.g., memory 140(1)) at a second time, the CCSM2 324,associated with the signal the RDM2 command 314, is received at thememory of the master memory unit at a third time; and the CCSS2 signal328, associated with the RDS2 command 318, is received at the memory ofthe slave memory unit at a fourth time.

The MASTER DATA 330 represents timing of the provision of data from thememory of a master memory unit responsive to a memory command directedto the master memory unit. For example, the first master data 332associated with the RDM1 command 312 is output from the memory of themaster memory unit responsive to receiving the CCSM1 signal 322, and thesecond master data 334 associated with the RDM2 command 314 is outputfrom the memory of the master memory unit responsive to receiving theCCSM2 signal 324.

The SLAVE DATA 340 represents timing of the provision of data from thememory of a slave memory unit responsive to a memory command directed tothe slave memory unit. For example, the first slave data 346 associatedwith the RDS1 command 316 is output from the memory of the slave memoryunit responsive to receiving the CCSS1 signal 326, and the second slavedata 348 associated with the RDS2 command 318 is output from the memoryof the slave memory unit responsive to receiving the CCSS2 signal 328.

As explained above, the master memory unit and the slave memory unit mayhave different timing characteristics, and, thus, tuning of provision ofdata from the memory of the master memory unit (e.g., MASTER DATA 330)and/or from memory of the slave memory unit (e.g., SLAVE DATA 340) isbased on the respective memory unit timing characteristics and on thetiming of receipt of the respective CCS signal 320 at a respectivememory

The DATA PIPELINE 350 represents a shared data pipeline for receivingdata from both the master memory unit and the slave memory unit. As isindicated in the example of FIG. 3, since the slave memory unit hasfaster timing characteristics that the master memory unit, the arrivalof the first slave data 356 (associated with the RDS1 command 316) atthe data pipeline overlaps a portion of the first master data 352(associated with the RDM1 command 312). This collision between the firstmaster data 352 and the first slave data 356 causes each of these dataat the data pipeline 350 to be destroyed. Similarly, the arrival of thesecond slave data 358 (associated with the RDS2 command 318) at the datapipeline overlaps a portion of the second master data 354 (associatedwith the RDM2 command 314), which causes each of these data to also bedestroyed.

Further, master control signals QINM 360 and slave control signals QINS370 correspond to the master data 330 and the slave data 340,respectively, which direct the data pipeline to store the received data,are dependent on the timing characteristics of the respective memoryunit. For example, the QINM1 signal 362 is provided to the data pipelinecontemporaneously with the first master data 352 and the QINS1 signal376 is provided to the data pipeline contemporaneously with the firstslave data 356. Thus, the QINM1 signal 362 may collide with the QINS1signal 376. Similarly, the QINM2 signal 364 is provided to the datapipeline contemporaneously with the second master data 354 and the QINS2signal 378 is provided to the data pipeline contemporaneously with thesecond slave data 358. Thus, the QINM2 signal 364 may collide with theQINS2 signal 378.

According to some embodiments of this disclosure, data collisions at thedata pipeline can be prevented by delaying the CCS signals 320 based onrelative differences hi timing characteristics between the memory units.Referring to FIG. 4, the memory commands 312, 314, 316, and 318 arereceived with similar timing as the memory commands 312, 314, 316, and318 of FIG. 3. Implementing a delay of the CCS signals 320, such asthrough the configurable delay circuit 130(0) or configurable delaycircuit 130(1) of FIG. 1, may prevent data output from the memory Of themaster memory unit and output from the memory of the slave memory unitfrom colliding at the DATA PIPELINE 350. For example, in the timingdiagram of FIG. 4, the data access timing of the memory of the slavememory unit is less than the data access timing of the memory of themaster memory unit As depicted in FIG. 4, the data associated with themaster read commands RDM1 312 and RDM2 314 are output as the firstmaster data 452 and second master data 454, respectively, as describedwith reference to FIG. 3.

Although the memory commands are received with similar timing asindicated in FIG. 3, the data associated with the slave memory commandsRDS1 316 and RDS2 318 are delayed. As shown in the exemplary timingdiagram of FIG. 4, the CCSS1 signal 426 and the CCSS2 signal 428 areeach delayed by a delay 406. The delay 496 increases a data access delayof the slave memory unit to approximate a liming characteristic of themaster memory unit (e.g., the slowest memory unit in this example), andmay be implemented us my the configurable delay circuit 130(1) of FIG. 1and/or the configurable delay circuit 230 of FIG. 2. The delay 490serves to delay downstream processing an associated memory command.Thus, by delaying provision of the CCSS1 signal 326, the first slavedata 346, the first slave data 356 (at the data pipeline), and the QINS1signal 376 are accordingly delayed by approximately the delay 496. FIG.4 illustrates the delayed data and signals as the CCSM signal 426, thefirst slave data 446, the first slave data 456 (at the data pipeline),and the QINS4 signal 476. Therefore, the first slave data 456 avoidscollision with the first master data 452 and the QINS1 signal 476 avoidscollision with the QINM1 signal 462. Similarly, by delaying provision ofthe CCSS2 signal 328, the second slave data 348, the second slave data358, and the QINS2 signal 378 are accordingly delayed by approximatelythe delay 496. FIG. 4 illustrates the delayed data and signals as CCSS2signal 428, the second slave data 448, the second slave data 458 (at thedata pipeline), and the QINS1 signal 476. Therefore, the second slavedata 458 avoids collision with the second master data 454 and the QINS2signal 478 avoids collision with the QINM2 signal 464.

The exemplary timing diagrams 300 and 400 are non-limiting illustrationsto provide a sufficient understanding of embodiments of the disclosure.It will be appreciated that the relative timing of the signals of theexemplary timing diagrams 300 and 400 may vary from multi-memory systemto multi-memory system, or within a multi-memory system. For example,the delay 496 may be less or greater than shown in the exemplary timingdiagram 400. Further, a data access time of the memory of tire mastermemory unit may be faster than a data access time of the memory of theslave memory unit, and thus the master memory unit may implement a delayto the associated CCS signals 320, while the slave memory unit mayimplement a minimal or no delay. The multi-memory system described inthe exemplary timing diagrams 300 and 400 may be expanded to includemore than two memory units, with each memory unit of the more than twomemories units including a delay of the associated CCS signal 320 basedon data timing characteristics of a respective memory unit relative totiming characteristics of a memory unit of the slowest memory unit ofthe more than two memory units.

As described, the length of the delays implemented to delay of the CCSsignals 320 via the configurable delay circuits (e.g., via theconfigurable delay circuit 130(0) and/or the configurable delay circuit130(1) of FIG. 1)) may be based on relative differences in tintingcharacteristics of each memory unit of a multi-memory system as comparedwith a slowest memory unit of a multi-memory system. Thus, relativetuning characteristics of each memory unit in a multi-memory system maybe measured to determine which memory unit of the multi-memory systemhas a slowest relative timing. The delays applied to remaining memoryunits in the multi-memory system are independently determined based onrelative differences in timing characteristics as compared with theslowest memory unit in the multi-memory system. Determining relativetiming characteristics of memory units in the multi-memory system may bedetermined using many different methodologies and architectures.

FIG. 5 provides one example of a timing characteristic measurementcircuit that may be used to determine relative timing characteristics ofmemory units of a multi-memory system The timing characteristicmeasurement circuit 500 of FIG. 5 uses two signals (e.g., INPUT1 andINPUT2) separated by a defined time gap to determine relative dataaccess timing of the memory of a memory unit.

As depicted in FIG. 5, the timing characteristic measurement circuit 500may include an input circuit 570. The input circuit is configured toreceive an input signal INPUT, a clock signal CLK, and a control signalCTRL. The input circuit 570 may include a first flip-flop FF 510 coupledto both a resistor-capacitor circuit RC 514 and a second FT 512. Thefirst FF 510 may be configured to receive the INPUT signal at an inputand the CLK signal at a clocking input, and to provide the INPUT1 signalat an output responsive to an edge of the CLK signal. The RC circuit maybe configured to receive the INPUT1 signal and provide an output to afirst input of a multiplexer 516. The second FF 512 may be configured toreceive an INPUT1 signal at an input and the CLK signal at a clockinginput, and to provide a signal to a second input of the multiplexer 516The multiplexer max be configured to provide the INPUT2 signal at anoutput having a logical value of the first input or the second inputbased on a value of the CTRL signal. For example, when the CTRL signalhas a first value, a logical value of the output of the RC circuit 514is provided at an output of the multiplexer 516, and when the CTRLsignal has a second value, a logical value of the output of the secondFF 512 is provided at an output of the multiplexer 510. In someembodiments, the second FF 512 may be used when a time differencebetween the INPUT1 signal and INPUT2 signal being a length of a periodof the CLK signal is sufficient, and the RC circuit 516 may be used whena time difference between the INPUT1 signal and INPUT2 signal isrequired to be greater than a period of the CLK signal.

The timing characteristic measurement circuit 500 may further includedelay units 502, 504, 506 and 508. Each delay unit 502, 504, 506 and 508may include a respective delay element 520, 522, 524, and 526 and arespective FF 530. The architecture of each of the delay units 502, 504,504, and 508 may be similar, with differences in a number of delay gatesin each respective delay element 520, 522, 524, and 526. As shown theINPUT1 signal is provided to the 16 gate (g) delay element 520 and to anA buffer BUFA 540 The output of the 16 g delay element is provided to aninput of the FF 530 via a first FF multiplexer 564 and to a B bufferBUFB 550. A multiplexes 560 receives the output of the BUFA 540 and theBUFB 550, and provides an output based on a signal received from a BIT0output of the FF 530. The output of the multiplexer 560 is provided toan 8 g delay element 522 and a BUFA 540 of a second delay unit 504.

The INPUT2 signal is provided to a second FF multiplexer 566, a B bufferBUFB 552, and an A buffer BUFA 542. The output of the second FFmultiplexer 566 is provided to a clocking input of the FF 530. The FF530 latches the BIT0 output at an output, which is provided to a controlinput of the multiplexer 560 and a control input of a multiplexer 562 ofthe first delay unit 502, and to the first FF multiplexer 564, thesecond FF multiplexer 566, the BUFB 552, and the BUFA 542 of the seconddelay unit 504.

The INPUT1 signal and the INPUT2 signal propagate through the thirddelay unit 500 and the fourth delay unit 508 similar to propagationthrough the first delay unit 502 and the second delay unit 508. Further,similar to the BIT0 output of the FF 550 of the first delay unit 502provided to the second delay unit 504, the BIT1 output from the FF 530of the second delay unit 504 is provided to the third delay unit 506,and the BIT2 output of the FF 530 of the third delay unit 506 ispresided to the fourth delay unit 508, and the BIT3 output is providedat an output of the FF 530 of the fourth delay unit 508.

In operation, as described above, the INPUT1 signal and the INPUT2signal are each provided to the delay units 502, 504, 506, and 508, andthe INPUT2 signal is delayed relative to the INPUT1 signal. The timingcharacteristic measurement circuit 500 is configured to perform a timingcharacteristic test to determine an approximate number of delay gatesnecessary to delay the INPUT1 signal such that timing of the INPUT1signal matches timing of the INPUT2 signal by propagating the INPUT1signal through a combination of the delay elements 520, 522, 524, and526. For example, the INPUT1 signal is propagated through the 16 g delay520 to an input of the FF 530. If the INPUT1 signal does not reach theinput of the FF 550 prior to the INPUT2 signal reaching the clockinginput of the FF 550, then the FF 530 latches the BIT0 output as a lowlogical value, indicating a delay applied to the INPUT1 signal is lessthan log to equal timing of the INPUT2 signal. Alternatively, if theINPUT1 signal reaches the input of the FF 530 prior to the INPUT2 signalreaching the clocking input of the FF 530, then the FF 530 latches theBIT0 output as a high logical value, indicating a delay applied to theINPUT1 signal must be at least 16 g to equal timing of the INPUT2signal.

In the case where the 16 g delay exceeds a delay necessary for timing ofthe INPUT1 signal to equal timing of the INPUT2 signal, the INPUT1signal is provided to the 8 g delay element 522 via BUFA 540 andmultiplexer 560 of the first delay unit 502 (e.g., the INPUT1 signalprovided to the second delay unit 504 bypasses the 16 g delay element520), and the INPUT2 signal is provided to the second delay unit 504 viathe BUFA 552 and the multiplexer 562 of the first delay unit. If theINPUT1 signal does not reach the input of the FF 530 prior to the INPUT2signal reaching the clocking input of the FF 530, then the FF 530latches the BIT1 output as a low logical value, indicating a delayapplied to the INPUT1 signal is less than an 8 g to equal timing of theINPUT2 signal. Alternatively, for the second delay unit 504, if theINPUT1 signal teaches the input of the FF 530 prior to the INPUT2 signalreaching the clocking input of the FF 530, then the FF 530 latches theBIT1 output as a high logical value, indicating a delay applied to theINPUT1 signal must be at least 8 g to equal timing of the INPUT2 signal.

In the case where a delay necessary to equalize timing of the INPUT1signal and the INPUTS signal is at least 16 g, the INPUT1 signal isprovided to the 8 g delay element 522 via the BUFB 550 and multiplexer560 of the first delay unit 502 (e.g., the INPUT1 signal provided to thesecond delay unit 504 is delayed through the 16 g delay element 520),and the INPUT2 signal is provided to the second delay unit 504 via theBUFB 552 and the multiplexer 562 of the first delay unit. If the INPUT1signal does not reach the input of the FF 530 prior to the INPUT2 signalreaching the clocking input of the FF 530. then the FF 530 latches theBIT1 output as a low logical value, indicating a delay applied to theINPUT1 signal is at least 16 g, but less than 24 g (e.g., 16 g+8 g) toequal timing of the INPUT2 signal. Alternatively, for the second delayunit 504, if the INPUT1 signal reaches the input of the FF 530 prior tothe INPUT2 signal reaching the clocking input of the FF 530, then the FF530 latches the BIT1 output as a high logical value, indicating a delayapplied to the INPUT1 signal must be at least 24 g to equal timing ofthe INPUT2 signal.

Propagation through the third delay unit 506 and the fourth delay unit508 continues similarly to propagation through the first delay unit 502and the second delay unit 504. Thus, the INPUT1 signal is propagatedthrough any combination of the delay elements 520, 522, 524, and 526 todetermine a delay in terms of a number of gates that approximates a timedelay between the INPUT1 signal and the INPUT2 signal, with a resolutionof two gates. A number represented by the BIT0/1/2/3 outputs mayindicate the number of gates that approximated the time delay. For amulti-memory system, each memory unit (e.g., the master memory unit 102and the slave memory unit 104 of FIG. 1) may implement the timingcharacteristic test using a respective timing characteristic measurementcircuit 500, and each memory unit may produce a respective count ofdelay gates that represents a delay between the INPUT1 signal and theINPUT2 signal. The respective counts may be compared to determine whichmemory unit has a smallest count, which may be identified as a slowestmemory unit. Relative timing differences between the slowest memory unitand each remaining memory units may be determined by comparing a countof gates of the slowest memory unit is a respective count of each of theremaining memory units. Thus, if the slowest memory unit had a count of4 g, and a particular memory unit had a count of 8 g, then theparticular memory unit is approximately 4 g faster or twice as fast overthe time period difference between the INPUT1 signal and INPUT2 signal.

As explained above, the timing characteristic measurement circuit 500described with reference to FIG. 5 is an example implementation fordetermining relative timing characteristic differences between memoryunits of a multi-memory system. Other timing methodologies andarchitectures may be used to determine relative timing characteristicdifferences. Further, the timing characteristic measurement circuit 500may be modified to include more or less delay units. The timingcharacteristic measurement circuit 500 may also be modified to includedelay elements having different delay gates than indicated in the delayelements 520, 522, 524, and 526, which may produce better or worseresolution than the timing characteristic measurement circuit 500 ofFIG. 5 (e.g., including a delay element with a single delay gate wouldincrease resolution to 1 g, or having a smallest delay element of 4 gwould decrease resolution to 4 g).

FIG. 6 illustrates a multi-memory system 600 according to an embodimentof the disclosure, in the embodiment shown, the multi-memory system 600is a stacked multi-memory system including a 4-high memory unit stack.Each memory unit includes a configurable delay circuit according to anembodiment of the present disclosure, such as the configurable delaycircuit 130(0) and or the configurable delay circuit 130(1) of FIG. 1and/or the configurable delay circuit 230 of FIG. 2. Further, themulti-memory system 600 may be configured to determine relative timingcharacteristic difference between each memory unit of the 4-high memoryunit stack, such as by including a timing characteristic measurementcircuit (e.g., the timing characteristic measurement circuit 500 of FIG.5). In the embodiment shown, the bottom memory unit may be designated asthe master memory unit 610(0), with a first slave memory unit 610(1),second slave memory unit 610(2), and third slave memory unit 610(3)stacked on top of it. As discussed above, memory groups according toembodiments of the present disclosure may be stacked in configurations8-high, 16-high, 32-high, and so on. In some configurations the memoryunits may be stacked directly on top of one another, while in others,they may be offset.

Those of ordinary skill would further appreciate that the variousillustrative logical blocks, configurations, circuits, and algorithmsteps described in connection with the embodiments disclosed herein maybe implemented as electronic hardware, computer software executed by aprocessor, or combinations of both. Various illustrative components,blocks, configurations, circuits, and steps have been described abovegenerally in terms of then functionality. Whether such functionality isimplemented as hardware or processor executable instructions dependsupon the particular application and design constraints imposed on theoverall system. Skilled artisans may implement the describedfunctionality in varying ways for each particular application, but suchimplementation decisions should not be interpreted as causing adeparture from the scope of the present disclosure.

The previous description of the disclosed embodiments is provided toenable a person skilled in the an to make or use the disclosedembodiments. Various modifications to these embodiments will be readilyapparent to those having ordinary skill in the art, and the principlesdefined herein may be applied to other embodiments without departingfrom the scope of the disclosure. Thus, the present disclosure is notintended to be limited to the embodiments shown herein but is to beaccorded the widest scope possible consistent with the principles andnovel features as defined by the following claims.

What is claimed is:
 1. A multi-memory system, comprising: a first memoryunit including first memory having first timing characteristics, thefirst memory unit configured to provide first column control signals tothe first memory based on a first memory command, the first mentorsconfigured to provide first read data responsive to receipt of the firstcolumn control signals; and a second memory unit including second memoryhaving second timing characteristics that are faster than the firsttiming characteristics, the second memory unit configured to providesecond column control signals to the second memory based on a secondmemory command, wherein receipt of the second column control signals atthe second memory may be delayed based on a difference between thesecond timing characteristics and the first timing characteristics, andthe second memory is configured to provide second read data responsiveto receipt of the second column control signals.
 2. The multi-memorysystem of claim 1, wherein the first memory unit further includes a datapipeline, wherein the data pipeline is configured to receive the firstread data from the first memory and the second read data from the secondmemory.
 3. The multi-memory system of claim 2, wherein the second memoryis coupled to the data pipeline by a through-silicon via.
 4. Themulti-memory system of claim 3, wherein the second memory unit isconfigured to provide a control signal to the data pipeline via a secondthrough-silicon via and wherein the data pipeline is farther configuredto store data received from the second memory unit.
 5. The multi-memorysystem of claim 1, wherein the first memory unit and the second memoryunit have the same architecture.
 6. The multi-memory system of claim 1,further comprising a plurality of additional memory units includingassociated memory having respective timing characteristics that arefaster than the first timing characteristics, wherein the plurality ofadditional memory units are configured to provide respective columncontrol signals to the associated memory based on a respective readcommand, and wherein receipt of the respective column control signals atthe associated memory may be delayed based on differences between therespective timing characteristics and the first timing characteristics.7. The multi-memory system of claim 1, wherein the second memory unitincludes a configurable delay circuit including delay gates, and whereinthe configurable delay circuit delays the second column control signalsby providing the second column control signals through at least one ofthe delay gates.
 8. The multi-memory system of claim 1, wherein thefirst memory unit includes a configurable delay circuit including delaygates, and wherein the configurable delay circuit delays the firstcolumn control signals by providing the first column control signalsthrough at least one of the delay gates.
 9. The multi-memory system ofclaim 1, wherein each of the first and second memory units includes aconfigurable delay circuit.
 10. The multi-memory system of claim 1,wherein the first and second timing characteristics are based onvariability in fabrication process.
 11. A multi-memory system,comprising: a first memory unit including a first configurable delaycircuit, the first memory unit including first memory having firsttiming characteristics, the first memory unit configured to provide fastcolumn control signals to the first memory based on a first memorycommand; and a second memory unit including second memory having secondtiming characteristics that are different than the first timingcharacteristics, the second memory unit configured to prevent acollision between first read data provided from the first memory andsecond read data provided from the second memory by adjusting secondcolumn control signals provided to the second memory.
 12. Themulti-memory system of claim 11, further comprising a plurality ofadditional memory units including associated memory having respectivetiming characteristics, wherein receipt of respective column controlsignals at the associated memory may be delayed based on differencesbetween the respective timing characteristics and the first timingcharacteristics, and wherein the respective timing characteristics ofthe associated memory are based on variability in fabrication process.13. The multi-memory system of claim 11, wherein receipt of the secondcolumn control signals at the second memory is delayed, and thecollision between the first read data provided from the first memory andthe second read data provided from the second memory is prevented due tothe delayed receipt of the second column control signals.
 14. Themulti-memory system of claim 11, wherein the first memory unit isdetermined to have a first timing characteristic of the first timingcharacteristics that is a number of gates slower than a second timingcharacteristic of the second timing characteristics for the secondmemory unit.
 15. The multi-memory system of claim 11, wherein the firstread data is provided by the first memory more slowly than the secondread data provided by the second memory.
 16. The multi-memory system ofclaim 15, wherein a delay of the second read data provided by the secondmemory is longer than a delay of the first read data provided by thefirst memory.
 17. A multi-memory system, comprising: a memory unitincluding memory having a timing characteristic and further including aconfigurable delay circuit; and an additional memory unit including anassociated memory having an additional timing characteristic, whereinreceipt of column control signals at the associated memory may bedelayed based on differences between the timing characteristic of thememory unit and the additional timing characteristic of the additionalmemory unit.
 18. The multi-memory system of claim 17, wherein the memoryunit is configured to provide column control signals to the memory basedon a memory command.
 19. The multi-memory system of claim 17, whereinthe memory is configured to provide first read data responsive toreceipt of column control signals.
 20. The multi-memory system of claim17, wherein the timing characteristic of the memory unit is slower thanthe additional timing characteristic of the additional memory unit.